In a couple of years, your child will reach a stage where she learns that those loving, mythical figures which are so often a part of childhood - Santa Claus and the Tooth Fairy - don't actually exist. This eventual realisation will happen whether you like it or not.
It usually stems from the hand-me-down knowledge of siblings or classmates with older siblings, who are delighted to break the news to the innocent, trusting younger generation.
And there are good psychological reasons why he believes in these mythical figures at this stage of her development.
First, they are benign, caring and generous. In addition, they apparently visit when she's asleep, at the time she's most vulnerable - and this makes them even more reassuring.
No wonder she accepts their existence without question - these fantasy characteristics help meet her deep-rooted psychological need to feel safe, loved and secure.
Second, they bring gifts! Your child willingly receives presents without question, and she has absolutely no motivation to interrupt the process.
As each mythical figure is tied to a specific time and event (Santa to Christmas, the Tooth Fairy to a tooth that has come out), she anticipates their arrival with great excitement. Drawing up an extensive present list for Santa Claus is one of the great rituals of early childhood.
A third explanation for her unquestioning belief in these fantasy characters is the social dimension. In particular, she enthusiastically discusses Santa's impending visit with you, her relatives and friends.
There is lots of talk about what she might get, her list of priorities, and what the "big ticket" item on her wish list will be. This shared experience, filled with warmth and excitement, adds to the fun.
For all these positive psychological reasons, most parents perpetuate the myth of Santa Claus and the Tooth Fairy for as long as possible, typically at least until their child starts school. This is perceived as fun for everyone in the family.
SHOULD YOU ENCOURAGE SUCH FALSE IDEAS?
However, some mums and dads take a completely different view, preferring not to encourage such false ideas in childhood.
And among these parents, there are those who would go so far as to claim that these mythical figures are simply lies, told by adults to deceive trusting children.
However, that is a rather extreme position. After all, a child's imagination develops in many different ways during the early years - for instance, when she starts to enjoy pretend-play, dressing-up play and role-play, or when she listens to fictional stories read to him by her parents.
Fantasy, therefore, is a rich, healthy and normal part of childhood. It's not a lie to read a child a fairy tale, even though the average three-year-old may easily think it is a true account of events.
Likewise, it's not a lie to stimulate her imagination through television programmes, songs and nursery rhymes, all of which involve imagination.
And the same applies when it comes to talking about Santa Claus and the Tooth Fairy with your child. Each of these positive, child-centred activities have an unreal element - in fact, that's what makes them so enjoyable.
You really cannot compare this to the deliberate malevolent act of giving a child misinformation in order to deceive. When talking about these mythical figures with your four-year-old, present them as warm, caring and friendly.
Of course, it's entirely up to you whether or not you introduce these characters at all. Whatever you decide, however, you can rest assured that by the time she is six, she'll have it all worked out anyway!
This article was first published in Young Parents.